A series of novel surfaces will be prepared by coating glow discharge polymers onto the interior surfaces of Silastic tubes (4 mm I.D., 5-10 feet long). The resulting ultrathin coatings (approximately 400 angstroms will provide continuous and coherent barrier layers, which will adhere tenaciously to the interior surfaces of the tubes. The physicochemical properties, such as the ratio of atoms on the surface, surface energy and its components, and permeability, of the coatings will be altered in a gradual manner (gradual change of surface properties) by changing the molecular structure of the starting materials within a selected series (e.g., perfluorcarbons) as well as the conditions of the glow discharge polymerization while maintaining the morphological or topographical aspects of the surfaces in a virtually unchanged condition. The intention is to produce surfaces that have highly thrombogenic to highly thromboresistant characteristics. ESCA, SEM, surface energy analysis, solubility analysis, and dyeing tests will be used to characterize the physicochemical aspects of the surfaces. The blood-surface interacton for such novel surfaces will be investigated by using the coated tubes for 1) whole blood clotting time tests with human blood, 2) the same tests with baboon blood, and 3) cannular platelet consumption rate determinations using an A-V shunt in baboons. Correlations of these test results with the physicochemical characteristics of the surfaces will be studied.